Flow sensors are widely used devices in various sectors of industry used for many purposes. Various types of sensors exist, such as air flow sensors, water flow sensors and particulate material flow sensors, etc.
Particularly in the agricultural sector with the growing need to produce increasingly higher grain yields, various methods and devices have come to be developed in order to improve the efficiency and accuracy of the application of seeds and inputs in the field. Due to this, flow sensors are one of the devices used in agricultural machinery with the objective of monitoring the flow of seed and/or inputs that are applied in the planting area.
One of the disadvantages presented by such flow sensors is related to the fact that they are sensitive to the accumulation of dust due to the downward movement of seeds and/or inputs in the conduits of agricultural machines, which leads to sensors functioning incorrectly.
Another apparent disadvantage is the fact that sensors send data to operator control interfaces, whether monitors or on-board computers, by means of wires routed through agricultural machinery, which are a constant source of faults and failures.
Furthermore, another apparent drawback is the fact that sensors require a level of power that makes it necessary for the power supply to be fed by means of wires connected to batteries or generators, which are also a source of faults and failures.
Listed below are some state-of-the-art technical documents and their disadvantages.
Patent document BR PI0301241-7 concerns an intelligent seed and fertilizer sensor, in particular, a current and voltage sensor, used to “detect” demand for seeds and fertilizer in mechanized distribution units, making it possible to determine whether or not the product is coming out of each containment vessel, as used in multi-line distribution machines, in order to avoid non-homogeneous distribution in a particular line, compromising the quality of planting.
One of the disadvantages presented by the system described above resides in the fact that the optical sensor exhibits reading failures due to the volume of dust generated by the flow of seeds and/or fertilizer within the conduit.
Patent document BR PI0704828-9 concerns an optical and/or ultrasonic reading system applied in planters for monitoring the outflow of seeds and fertilizers in which an optical or ultrasonic sensor is positioned between a semiconductor and the seed conductor within the main body and next to the individual reservoir, featuring an optical or ultrasonic sensor close to the blade or double plough disc of fertilizers and between the fertilizer conductor and the sleeve, in which the sensors have signal transmitters and receptors placed within a housing and protected by transparent plaques configured in such a way as to emit rays and occupy the entire space of the section for the passage of products.
The optical and/or ultrasonic reading system described in the above document diverges frontally from that as recommended by the sensor subject to the present invention due to the use of an optical and/or ultrasonic sensor. In addition, such detection technologies are also greatly affected by the layers of material deposited above the sensors within the conduit.
Patent document BR PI0923975-8 describes a microprocessor-controlled method and system used to detect the presence of solid inputs, basically comprised of a main capacitive sensor, microcontrollers and other devices whereas the system processes the data measured and emits signals to various external devices, such as light-emitting diodes (LEDs), sirens, on-board computers, machine control panels and wireless signal receptors. This system uses specific methods to create detection parameters that, in addition to detecting solid inputs, also eliminates the possibility of false alarms that arise from the presence of small layers of dirt, such as dust or fertilizer crusts that eventually may come to be deposited on the sensors and that are normally detected by the sensors as an input stream and not as dirt deposited on the sensor.
The system and method used for the detection of solid inputs by way of capacitive sensors, as described in the aforementioned document, presents some drawbacks, among which are highlighted the requirement for wires to supply the sensors with a power feed, due to their high energy consumption.
Patent document BR PI0201720-2 describes a solid mass flow sensor that provides for the perfect monitoring of solid mass flows and even indicates when the system is clogged up. Its application is for the monitoring of any solid mass flow, independent of granulation or texture, and for any solid mass applicator equipment. Its use is particularly for, although not limited to, the monitoring of fertilizer solid flows being provided with a transducer, which may be a microphone, buzzer or any type of vibration or sound pick-up. This transducer can directly intercept the mass flow, be coupled externally or internally to the conduit that carries the mass flow, can be simply close to the mass flow or can be laid alongside or close to cords that intercept the mass flow and transmit vibrations or sound to the transducer. The transducer then captures the vibrations or sounds and transforms them into electrical signals that are amplified and filtered and turned into electronic signals, such are then conducted to a control panel, which includes a calibrator button via that the operator will control the ideal conditions for the mass flow and that may also contain LEDs or displays to inform the operator about the conditions of the mass flow.
The flow sensor described in the above document presents some drawbacks among which are highlighted the absence of a resonate element installed in the conduit that guides the particulate material, to enhance the pick-up of mechanical vibrations due to collisions between particles within the flow and the conduit. Another deficiency in the technique as described in the above document resides in the fact that the transducer is not provided with a shield so as to impede incidences of external vibrations, which can result in malfunctioning of the transducer.
The initial proposal for a solid fertilizer flow sensor, such as described in the patent document PI0201720-2, resulted in the development of a wireless particulate solid materials flow sensor, the subject of this invention, the main purpose of which is to monitor the flow of particulate material within a tubular conduit during operation of equipment and/or machinery and that alerts the operator when the flow is irregular or interrupted.
Patent documents U.S. Pat. Nos. 5,831,539 and 5,831,542 describe a specialized sensor for the flow of seeds, provided with a passive piezoelectric type transducer inserted at an angle within a tubular conduit for seeds, in such a way that seeds collide directly with the transducer at an angle that captures the vibrations of such collisions.
Patent document U.S. Pat. No. 4,441,101 describes a specialized sensor for the flow of seeds that consists of a pin with one end coupled to a piezoelectric transducer. The other end of the pin is positioned internally to the seed flow conduit in such a way that vibrations that originate from collisions between the pin and seeds are captured by the piezoelectric transducer.
Patent document U.S. Pat. No. 4,079,362 describes a specialized sensor for the flow of seeds and fertilizers fed by gravity in which a piezoelectric transducer is positioned in the path of the falling particulate material, in such a way that the particulate material directly impacts the transducer, thereby generating an electrical signal in response to collisions between the material and the transducer.
The flow sensors described in the aforementioned documents present some drawbacks, among which are highlighted the fact that such sensing methods are done in an invasive manner, that is to say, the transducer itself interrupts the flow of seeds, thereby causing disturbance within the flow and mechanical damage to the seeds. This effect is more pronounced in systems that generate flow by way of air pressure where the material travels through conduits at high speed.
Additionally, invasive flow sensing is handicapped due to the fact that dirt, dust and chemical treatments present among seeds are deposited on the transducers or on the walls that support such, reducing efficiency and reliability. This disadvantage compromises the sensing of fertilizer solid flows even more, given that in the presence of humidity, the particulate material may be deposited and adhere to the transducer or on the walls that support such, a phenomenon known as crusting, which prejudices their function.
Patent document US 07450019B1 describes a flow sensor for material transported by pneumatic pressure, provided with a piezoelectric transducer coupled to a flow deflector that captures vibrations that originated from the collision between particulate material and the deflector.
The flow sensor described in the aforementioned document presents some drawbacks, among which we highlight the fact that the sensor is applied to a specific material dosing system supplied with a deflector. Additionally, deposition of material on the deflector can prejudice the detection of vibrations. In addition, there is the further disadvantage of not having any type of protection or isolation for the transducer-deflector assembly which is subject to the erroneous capture of vibrations that arise from the structure of the machine and from external impacts.
Patent document US 08950260B2 describes a flow sensor for seeds fed by pneumatic pressure. The sensor is provided with a curved conduit in which an acoustic transducer is coupled which generates sound waves in response to collisions from seeds with the transducer, whereas these sonic waves are transported via a duct to an electromechanical transducer which transforms sound into electrical signals for later processing.
The flow sensor described in the aforementioned document presents some drawbacks, among which we highlight the fact that the sensor imposes an abrupt change in the direction of flow which generates pressure drops in the pneumatic system and thereby leads to damage to seeds and any treatments applied to them. Furthermore, the geometry of the system favors the deposition of material in front of the acoustic transducer, such as dust, dirt, and chemical treatments among others which prejudices its function. Additionally, it contains a series of rubber tubes placed in each sensor which burdens the product making it difficult to install and which can lead to the need for maintenance. Another drawback is the need for an external energy supply for the system to function which in itself leads to the need to accommodate cables for agricultural equipment with all the known problems associated with this type of solution.
Patent document US 04057709 describes a flow sensor for seeds transported by pneumatic pressure or by gravity, provided with an angled tubular conduit in which a piezoelectric transducer is glued or cemented which further possesses coupled rubber impact absorbers at the extremities of the tubular conduit. The angulation of the tubular conduit means that the flow is predominately incident on the area where the transducer is positioned, in order that electrical signals may be generated by it in response to the impact of particulate material.
The flow sensor described in the aforementioned document presents some drawbacks, among which we highlight the fact that the transducer is fixed solidly (glued or cemented) to the tubular conduit without any rear support in such a way that it vibrates together with the tubular conduit whereby it has a substantially reduced detection capacity. Such a deficiency requires that for satisfactory detection, it is necessary for the conduit to be angled so that the flow of seeds focuses predominately in the area of the transducer. However, such angulation has the disadvantage of leading to a loss of pneumatic pressure in the system, as well as favoring the deposition of material alongside the detection area of the sensor itself. These problems prejudice its function of flow detection in the presence of dust which is characteristic in the dosage of solid fertilizer or with dirt or chemical treatment commonly present in seeds. Furthermore, it comprises of only one transducer within the tube and therefore its isolation is a deficiency as it comprises only rubberized material without counting on a more specific format for more efficient noise isolation.
A simplified summary of the method described for the present invention will appear below, whereas this summary does not provide an extensive overview of all the methods contemplated herein. Furthermore, it is not intended to identify key or critical elements, nor outline the scope of the method. Its sole purpose is to present some of the concepts for the method described in a simplified manner, in such a way as to act as an introduction to the more detailed description that will be presented subsequently.